No. 77: Sep-Oct 1991
What happens when two white dwarf stars in close orbit finally fall into one another? Theory says you get a colossal explosion called a Type-I supernova. But this hypothesis is in trouble because a recent survey of white dwarfs revealed absolutely no double white dwarfs in a sampe of 25 from the Milky Way. Even if a few pairs are eventually found, they do not appear to be numerous enough to account for the rate at which supernovas are observed.
(Crosswell, Ken; "Supernova Theory Exploded by Solitary White Dwarfs," New Scientist, p. 23, March 23, 1991.)